The identification of molecules relevant to human health not only improves the chances for new therapeutic approaches, but can also reveal critical insight into the etiology underlying disease. Forward genetic screens in vertebrates have greatly aided in our understanding of biological processes and disease, and we aim to expand the ability of the zebrafish community to screen for components critical to development and function. We propose to adapt two new screening methods 'BioID' and 'Isolation of Nuclei TAgged in specific Cell Types' (INTACT) for use with zebrafish. Both techniques involve tissue-specific biotinylation of nuclei or proteins that occurs in vivo before processing of samples, and both techniques offer several advantages over current methods. For the BioID method, we will generate versions of the Tol2 Gateway vector that can accommodate any promoter and/or protein of interest. For the INTACT method, our aim is to generate stable transgenic lines that would enable the community to use Gal4 lines already available as a means of achieving tissue specificity. We will also generate a stable line that ubiquitously expresses the biotin ligase for those laboratories that wish to use a specific promoter. For both approaches, we will develop simple protocols for post-in vivo expression steps using zebrafish embryos and larvae as the source of material for purification and identification of novel factors.